Revert "[webpack-encore-bundle] disable strict_mode by default (#1087)" (#1099)

This reverts commit 4995ec2.

Author: nicolas-grekas

symfony/webpack-encore-bundle/1.10/config/packages/webpack_encore.yaml

@@ -20,8 +20,8 @@ webpack_encore:
     # Preload all rendered script and link tags automatically via the HTTP/2 Link header
     # preload: true
 
-    # Set to true to throw an exception if the entrypoints.json file is missing or an entry is missing from the data
-    strict_mode: false
+    # Throw an exception if the entrypoints.json file is missing or an entry is missing from the data
+    # strict_mode: false
 
     # If you have multiple builds:
     # builds: