Problems reported:

parser/coverage/numbers:4:7: Expected an identifier, but got ';'.
  12_.;
      ^

parser/coverage/numbers:2:3: Digit separators ('_') in a number literal can only be placed between two digits.
  12_e;
  ^

parser/coverage/numbers:2:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  12_e;
  ^

parser/coverage/numbers:3:3: Digit separators ('_') in a number literal can only be placed between two digits.
  12_E;
  ^

parser/coverage/numbers:3:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  12_E;
  ^

parser/coverage/numbers:4:3: Digit separators ('_') in a number literal can only be placed between two digits.
  12_.;
  ^

parser/coverage/numbers:5:3: Digit separators ('_') in a number literal can only be placed between two digits.
  12_;
  ^

parser/coverage/numbers:6:3: Digit separators ('_') in a number literal can only be placed between two digits.
  0x_;
  ^

parser/coverage/numbers:6:3: A hex digit (0-9 or A-F) must follow '0x'.
  0x_;
  ^

parser/coverage/numbers:7:3: Digit separators ('_') in a number literal can only be placed between two digits.
  0xA_;
  ^

parser/coverage/numbers:9:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2_;
  ^

parser/coverage/numbers:10:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2_e;
  ^

parser/coverage/numbers:10:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  1.2_e;
  ^

parser/coverage/numbers:11:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2_E;
  ^

parser/coverage/numbers:11:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  1.2_E;
  ^

parser/coverage/numbers:12:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2e_;
  ^

parser/coverage/numbers:12:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  1.2e_;
  ^

parser/coverage/numbers:13:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2E_;
  ^

parser/coverage/numbers:13:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  1.2E_;
  ^

parser/coverage/numbers:14:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2e-_;
  ^

parser/coverage/numbers:14:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  1.2e-_;
  ^

parser/coverage/numbers:15:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2E-_;
  ^

parser/coverage/numbers:15:3: Numbers in exponential notation should always contain an exponent (an integer number with an optional sign).
  1.2E-_;
  ^

parser/coverage/numbers:16:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2e-1_;
  ^

parser/coverage/numbers:17:3: Digit separators ('_') in a number literal can only be placed between two digits.
  1.2E-1_;
  ^

beginCompilationUnit(void)
  beginMetadataStar(void)
  endMetadataStar(0)
  beginTopLevelMember(void)
    beginTopLevelMethod(UnterminatedToken(UnexpectedSeparatorInNumber), null, null)
      handleVoidKeyword(void)
      handleIdentifier(foo, topLevelFunctionDeclaration)
      handleNoTypeVariables(()
      beginFormalParameters((, MemberKind.TopLevelMethod)
      endFormalParameters(0, (, ), MemberKind.TopLevelMethod)
      handleAsyncModifier(null, null)
      beginBlockFunctionBody({)
        handleLiteralDoubleWithSeparators(12_e0)
        handleExpressionStatement(12_e0, ;)
        handleLiteralDoubleWithSeparators(12_E0)
        handleExpressionStatement(12_E0, ;)
        handleLiteralIntWithSeparators(12_)
        handleRecoverableError(Message[ExpectedIdentifier, Expected an identifier, but got ';'., Try inserting an identifier before ';'., {lexeme: ;}], ;, ;)
        handleIdentifier(, expressionContinuation)
        handleNoTypeArguments(;)
        handleNoArguments(;)
        handleSend(, )
        handleEndingBinaryExpression(., )
        handleExpressionStatement(12_, ;)
        handleLiteralIntWithSeparators(12_)
        handleExpressionStatement(12_, ;)
        handleLiteralInt(0x_0)
        handleExpressionStatement(0x_0, ;)
        handleLiteralIntWithSeparators(0xA_)
        handleExpressionStatement(0xA_, ;)
        handleLiteralDouble(.1)
        handleExpressionStatement(.1, ;)
        handleLiteralDoubleWithSeparators(1.2_)
        handleExpressionStatement(1.2_, ;)
        handleLiteralDoubleWithSeparators(1.2_e0)
        handleExpressionStatement(1.2_e0, ;)
        handleLiteralDoubleWithSeparators(1.2_E0)
        handleExpressionStatement(1.2_E0, ;)
        handleLiteralDoubleWithSeparators(1.2e_0)
        handleExpressionStatement(1.2e_0, ;)
        handleLiteralDoubleWithSeparators(1.2E_0)
        handleExpressionStatement(1.2E_0, ;)
        handleLiteralDoubleWithSeparators(1.2e-_0)
        handleExpressionStatement(1.2e-_0, ;)
        handleLiteralDoubleWithSeparators(1.2E-_0)
        handleExpressionStatement(1.2E-_0, ;)
        handleLiteralDoubleWithSeparators(1.2e-1_)
        handleExpressionStatement(1.2e-1_, ;)
        handleLiteralDoubleWithSeparators(1.2E-1_)
        handleExpressionStatement(1.2E-1_, ;)
      endBlockFunctionBody(16, {, })
    endTopLevelMethod(void, null, })
  endTopLevelDeclaration(})
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(ExpectedHexDigit))
  handleRecoverableError(ExpectedHexDigit, UnterminatedToken(ExpectedHexDigit), UnterminatedToken(ExpectedHexDigit))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(MissingExponent))
  handleRecoverableError(MissingExponent, UnterminatedToken(MissingExponent), UnterminatedToken(MissingExponent))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
  handleErrorToken(UnterminatedToken(UnexpectedSeparatorInNumber))
  handleRecoverableError(UnexpectedSeparatorInNumber, UnterminatedToken(UnexpectedSeparatorInNumber), UnterminatedToken(UnexpectedSeparatorInNumber))
endCompilationUnit(1, )