Problems reported:

parser/error_recovery/issue_48288:2:5: Expected an identifier, but got ':'.
  g(: 1, bbb: 0);
    ^

beginCompilationUnit(void)
  beginMetadataStar(void)
  endMetadataStar(0)
  beginTopLevelMember(void)
    beginTopLevelMethod(, null, null)
      handleVoidKeyword(void)
      handleIdentifier(f, topLevelFunctionDeclaration)
      handleNoTypeVariables(()
      beginFormalParameters((, MemberKind.TopLevelMethod)
        beginMetadataStar(int)
        endMetadataStar(0)
        beginFormalParameter(int, MemberKind.TopLevelMethod, null, null, null)
          handleIdentifier(int, typeReference)
          handleNoTypeArguments(x)
          handleType(int, null)
          handleIdentifier(x, formalParameterDeclaration)
          handleFormalParameterWithoutValue())
        endFormalParameter(null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.TopLevelMethod)
      endFormalParameters(1, (, ), MemberKind.TopLevelMethod)
      handleAsyncModifier(null, null)
      beginBlockFunctionBody({)
        handleIdentifier(g, expression)
        handleNoTypeArguments(()
        beginArguments(()
          handleRecoverableError(Message[ExpectedIdentifier, Expected an identifier, but got ':'., Try inserting an identifier before ':'., {lexeme: :}], :, :)
          handleIdentifier(, namedArgumentReference)
          handleLiteralInt(1)
          handleNamedArgument(:)
          handleIdentifier(bbb, namedArgumentReference)
          handleLiteralInt(0)
          handleNamedArgument(:)
        endArguments(2, (, ))
        handleSend(g, ;)
        handleExpressionStatement(;)
      endBlockFunctionBody(1, {, })
    endTopLevelMethod(void, null, })
  endTopLevelDeclaration()
endCompilationUnit(1, )