Fix lost diags across different mutators (#2057)

## Changes
Fix cases where accumulated diagnostics are lost instead of being
propagated further. In some cases it's not possible, add a comment
there.

## Tests
Existing tests

bundle/artifacts/expand_globs.go

@@ -97,7 +97,7 @@ func (m *expandGlobs) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagnost
 		return dyn.SetByPath(v, base, dyn.V(output))
 	})
 	if err != nil {
-		return diag.FromErr(err)
+		diags = diags.Extend(diag.FromErr(err))
 	}
 
 	return diags

bundle/config/mutator/resolve_resource_references.go

@@ -40,6 +40,7 @@ func (m *resolveResourceReferences) Apply(ctx context.Context, b *bundle.Bundle)
 		})
 	}
 
+	// Note, diags are lost from all goroutines except the first one to return diag
 	return diag.FromErr(errs.Wait())
 }
 

bundle/config/root.go

@@ -102,7 +102,8 @@ func LoadFromBytes(path string, raw []byte) (*Root, diag.Diagnostics) {
 	// Convert normalized configuration tree to typed configuration.
 	err = r.updateWithDynamicValue(v)
 	if err != nil {
-		return nil, diag.Errorf("failed to load %s: %v", path, err)
+		diags = diags.Extend(diag.Errorf("failed to load %s: %v", path, err))
+		return nil, diags
 	}
 	return &r, diags
 }

bundle/config/validate/folder_permissions.go

@@ -36,7 +36,8 @@ func (f *folderPermissions) Apply(ctx context.Context, b bundle.ReadOnlyBundle)
 	}
 
 	if err := g.Wait(); err != nil {
-		return diag.FromErr(err)
+		// Note, only diag from first coroutine is captured, others are lost
+		diags = diags.Extend(diag.FromErr(err))
 	}
 
 	for _, r := range results {