Problems reported:

parser/error_recovery/issue_39202.crash:1:1: Expected a declaration, but got '('.
() async => a b < c $? >
^

parser/error_recovery/issue_39202.crash:1:2: Expected a declaration, but got ')'.
() async => a b < c $? >
 ^

parser/error_recovery/issue_39202.crash:1:4: A function declaration needs an explicit list of parameters.
() async => a b < c $? >
   ^^^^^

parser/error_recovery/issue_39202.crash:1:13: Expected ';' after this.
() async => a b < c $? >
            ^

parser/error_recovery/issue_39202.crash:1:19: Expected '>' after this.
() async => a b < c $? >
                  ^

parser/error_recovery/issue_39202.crash:1:25: Expected an identifier, but got ''.
() async => a b < c $? >
                        ^...

parser/error_recovery/issue_39202.crash:1:25: Expected ';' after this.
() async => a b < c $? >
                        ^...

beginCompilationUnit(()
  beginMetadataStar(()
  endMetadataStar(0)
  beginTopLevelMember(()
    handleRecoverableError(Message[ExpectedDeclaration, Expected a declaration, but got '('., null, {token: (}], (, ()
    handleInvalidTopLevelDeclaration(()
  endTopLevelDeclaration())
  beginMetadataStar())
  endMetadataStar(0)
  beginTopLevelMember())
    handleRecoverableError(Message[ExpectedDeclaration, Expected a declaration, but got ')'., null, {token: )}], ), ))
    handleInvalidTopLevelDeclaration())
  endTopLevelDeclaration(async)
  beginMetadataStar(async)
  endMetadataStar(0)
  beginTopLevelMember(async)
    beginTopLevelMethod(), null)
      handleNoType())
      handleIdentifier(async, topLevelFunctionDeclaration)
      handleNoTypeVariables(=>)
      handleRecoverableError(MissingFunctionParameters, async, async)
      beginFormalParameters((, MemberKind.TopLevelMethod)
      endFormalParameters(0, (, ), MemberKind.TopLevelMethod)
      handleAsyncModifier(null, null)
      handleIdentifier(a, expression)
      handleNoTypeArguments(b)
      handleNoArguments(b)
      handleSend(a, b)
      handleRecoverableError(Message[ExpectedAfterButGot, Expected ';' after this., null, {string: ;}], a, a)
      handleExpressionFunctionBody(=>, ;)
    endTopLevelMethod(async, null, ;)
  endTopLevelDeclaration(b)
  beginMetadataStar(b)
  endMetadataStar(0)
  beginTopLevelMember(b)
    handleIdentifier(b, typeReference)
    beginTypeArguments(<)
      handleIdentifier(c, typeReference)
      handleNoTypeArguments($)
      handleType(c, null)
      handleRecoverableError(Message[ExpectedAfterButGot, Expected '>' after this., null, {string: >}], c, c)
    endTypeArguments(1, <, >)
    handleType(b, null)
    handleRecoverableError(Message[ExpectedIdentifier, Expected an identifier, but got ''., null, {token: }], , )
    handleIdentifier(, topLevelVariableDeclaration)
    handleNoFieldInitializer()
    handleRecoverableError(Message[ExpectedAfterButGot, Expected ';' after this., null, {string: ;}], , )
  endTopLevelFields(null, null, null, null, null, 1, b, ;)
endTopLevelDeclaration()
endCompilationUnit(4, )