Problems reported:

parser/general/call_on_after_try_block2:12:7: A record type with exactly one positional field requires a trailing comma.
  on(e) {
      ^

parser/general/call_on_after_try_block2:15:6: Expected a type, but got '""'.
  on("");
     ^^

parser/general/call_on_after_try_block2:15:6: Expected ')' before this.
  on("");
     ^^

parser/general/call_on_after_try_block2:15:8: A record type with exactly one positional field requires a trailing comma.
  on("");
       ^

parser/general/call_on_after_try_block2:15:8: A catch clause must have a body, even if it is empty.
  on("");
       ^

beginCompilationUnit(void)
  beginMetadataStar(void)
  endMetadataStar(0)
  beginTopLevelMember(void)
    beginTopLevelMethod(, null, null)
      handleVoidKeyword(void)
      handleIdentifier(main, topLevelFunctionDeclaration)
      handleNoTypeVariables(()
      beginFormalParameters((, MemberKind.TopLevelMethod)
      endFormalParameters(0, (, ), MemberKind.TopLevelMethod)
      handleAsyncModifier(null, null)
      beginBlockFunctionBody({)
        beginTryStatement(try)
          beginBlock({, BlockKind(try statement))
            handleEmptyStatement(;)
          endBlock(1, {, }, BlockKind(try statement))
          beginCatchClause(catch)
            beginFormalParameters((, MemberKind.Catch)
              beginMetadataStar(e)
              endMetadataStar(0)
              beginFormalParameter(e, MemberKind.Catch, null, null, null)
                handleNoType(()
                handleIdentifier(e, formalParameterDeclaration)
                handleFormalParameterWithoutValue())
              endFormalParameter(null, null, null, e, null, null, FormalParameterKind.requiredPositional, MemberKind.Catch)
            endFormalParameters(1, (, ), MemberKind.Catch)
          endCatchClause({)
          beginBlock({, BlockKind(catch clause))
            handleEmptyStatement(;)
          endBlock(1, {, }, BlockKind(catch clause))
          handleCatchBlock(null, catch, null)
          beginCatchClause(on)
            handleIdentifier(Foo, typeReference)
            handleNoTypeArguments({)
            handleType(Foo, null)
          endCatchClause({)
          beginBlock({, BlockKind(catch clause))
            handleEmptyStatement(;)
          endBlock(1, {, }, BlockKind(catch clause))
          handleCatchBlock(on, null, null)
          beginCatchClause(on)
            beginRecordType(()
              beginRecordTypeEntry()
                beginMetadataStar(e)
                endMetadataStar(0)
                handleIdentifier(e, typeReference)
                handleNoTypeArguments())
                handleType(e, null)
                handleNoName())
              endRecordTypeEntry()
              handleRecoverableError(RecordTypeOnePositionalFieldNoTrailingComma, ), ))
            endRecordType((, null, 1, false)
          endCatchClause({)
          beginBlock({, BlockKind(catch clause))
            handleEmptyStatement(;)
          endBlock(1, {, }, BlockKind(catch clause))
          handleCatchBlock(on, null, null)
          beginCatchClause(on)
            beginRecordType(()
              beginRecordTypeEntry()
                beginMetadataStar("")
                endMetadataStar(0)
                handleRecoverableError(Message[ExpectedType, Expected a type, but got '""'., null, {lexeme: ""}], "", "")
                handleIdentifier(, typeReference)
                handleNoTypeArguments("")
                handleType(, null)
                handleNoName("")
              endRecordTypeEntry()
              handleRecoverableError(Message[ExpectedButGot, Expected ')' before this., null, {string: )}], "", "")
              handleRecoverableError(RecordTypeOnePositionalFieldNoTrailingComma, ), ))
            endRecordType((, null, 1, false)
          endCatchClause(;)
          handleRecoverableError(ExpectedCatchClauseBody, ), ))
          beginBlock({, BlockKind(catch clause))
          endBlock(0, {, }, BlockKind(catch clause))
          handleCatchBlock(on, null, null)
        endTryStatement(4, try, null, })
        handleEmptyStatement(;)
      endBlockFunctionBody(2, {, })
    endTopLevelMethod(void, null, })
  endTopLevelDeclaration(})
endCompilationUnit(1, )