fix: respect errors and warnings from minimizer without code

Author: alexander-akait

package-lock.json

@@ -622,7 +622,7 @@ class CssMinimizerPlugin {
                 innerSourceMap,
                 true,
               );
-            } else {
+            } else if (item.code) {
               output.source = new RawSource(item.code);
             }
           }
@@ -632,7 +632,7 @@ class CssMinimizerPlugin {
               inputSourceMap && CssMinimizerPlugin.isSourceMap(inputSourceMap);
 
             for (const error of result.errors) {
-              output.warnings.push(
+              output.errors.push(
                 CssMinimizerPlugin.buildError(
                   error,
                   name,
@@ -691,6 +691,10 @@ class CssMinimizerPlugin {
           }
         }
 
+        if (!output.source) {
+          return;
+        }
+
         const newInfo = { minimized: true };
         const { source } = output;
 

src/index.js

@@ -34,8 +34,10 @@ async function minify(options) {
     );
 
     if (typeof minifyResult.code !== "string") {
-      throw new Error(
-        "minimizer function doesn't return the 'code' property or result is not a string value",
+      result.errors.push(
+        new Error(
+          "minimizer function doesn't return the 'code' property or result is not a string value",
+        ),
       );
     }