Catch scanner error when possible to avoid bypass (#36963)

cmd/hook.go

@@ -276,6 +276,9 @@ Gitea or set your environment appropriately.`, "")
 			lastline = 0
 		}
 	}
+	if err := scanner.Err(); err != nil {
+		return fail(ctx, "Hook failed: stdin read error", "scanner error: %v", err)
+	}
 
 	if count > 0 {
 		hookOptions.OldCommitIDs = oldCommitIDs[:count]
@@ -415,6 +418,11 @@ Gitea or set your environment appropriately.`, "")
 			count = 0
 		}
 	}
+	if err := scanner.Err(); err != nil {
+		_ = dWriter.Close()
+		hookPrintResults(results)
+		return fail(ctx, "Hook failed: stdin read error", "scanner error: %v", err)
+	}
 
 	if count == 0 {
 		if wasEmpty && masterPushed {