[lld] [LLD] Fix crash on parsing ':ALIGN' in linker script (PR #146723)

[via llvm-commits]

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@@ -1229,6 +1229,9 @@ SymbolAssignment *ScriptParser::readSymbolAssignment(StringRef name) {
 // This is an operator-precedence parser to parse a linker
 // script expression.
 Expr ScriptParser::readExpr() {
+  // Do not try to read expression if an error has already been encountered.
+  if (atEOF())
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parth-07 wrote:

Thank you for your inputs @smithp35.

> although I think it may be more idiomatic to use
>
```
 if (errCount(ctx))
   return 0;
```

I agree that `errCount(ctx)` would work as well, however, I think it is better for code-readability if the behavior of parsing expression is consistent for both the error-case and the actual end-of-file case, and `atEOF()` covers both the cases. Please let me know your thoughts on this. 

https://github.com/llvm/llvm-project/pull/146723