Fix Go extractor silent failures and improve error recovery

The extractor was calling log.Fatal() when file extraction failed, causing
the entire extraction process to terminate silently on the first error. This
was particularly problematic for OOM errors which would only appear in
build-tracer logs, not in the extractor output.

Changes:
- Replace log.Fatal() with log.Printf() to log errors without terminating
- Add panic recovery in file extraction goroutines to catch OOM errors
- Move cleanup (semaphore release, WaitGroup.Done) into defer block to
  ensure proper cleanup even when panics occur

This allows extraction to continue processing remaining files when individual
files fail, and ensures errors are visible in extractor logs.

Author: allsmog

go/extractor/extractor.go

@@ -706,12 +706,18 @@ func (extraction *Extraction) extractPackage(pkg *packages.Package) {
 		extraction.WaitGroup.Add(1)
 		extraction.GoroutineSem.acquire(1)
 		go func(astFile *ast.File) {
+			defer func() {
+				if r := recover(); r != nil {
+					log.Printf("Panic during file extraction in package %s: %v", pkg.PkgPath, r)
+				}
+				extraction.GoroutineSem.release(1)
+				extraction.WaitGroup.Done()
+			}()
+
 			err := extraction.extractFile(astFile, pkg)
 			if err != nil {
-				log.Fatal(err)
+				log.Printf("Error extracting file in package %s: %v", pkg.PkgPath, err)
 			}
-			extraction.GoroutineSem.release(1)
-			extraction.WaitGroup.Done()
 		}(astFile)
 	}
 }