Report pending errors from MetalCodeGenerator

This mirrors the change in https://skia-review.googlesource.com/c/skia/+/441311,
but for Metal this time.

Change-Id: I1abdb844b6392c81252532f9ff4a91b993edb66e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/441401
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
index 9431ae6..af97607 100644
--- a/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
+++ b/src/sksl/codegen/SkSLMetalCodeGenerator.cpp
@@ -2614,6 +2614,7 @@
     write_stringstream(fExtraFunctionPrototypes, *fOut);
     write_stringstream(fExtraFunctions, *fOut);
     write_stringstream(body, *fOut);
+    fContext.fErrors->reportPendingErrors(PositionInfo());
     return fContext.fErrors->errorCount() == 0;
 }