Add template information to multiple template error messages. (#2115)

* Add template information to multiple template error messages.

In service of helping debug #2114,
this change fleshes out the template error messages to include
the current list of templates.

* add newline

docs/CHANGELOG.md

@@ -10,6 +10,10 @@ nav_order: 5
 
 ## main
 
+* Add template information to multiple template error messages.
+
+    *Joel Hawksley*
+
 * Add `ostruct` to gemspec file to suppress stdlib removal warning.
 
     *Jonathan Underwood*

lib/view_component/compiler.rb

@@ -159,7 +159,7 @@ def gather_template_errors(raise_errors)
         errors << "Colliding templates #{variant_names.sort.map { |v| "'#{v}'" }.to_sentence} found in #{@component}."
       end
 
-      raise TemplateError.new(errors) if errors.any? && raise_errors
+      raise TemplateError.new(errors, @templates) if errors.any? && raise_errors
 
       errors
     end

lib/view_component/errors.rb

@@ -17,8 +17,16 @@ def initialize(klass_name)
   end
 
   class TemplateError < StandardError
-    def initialize(errors)
-      super(errors.join("\n"))
+    def initialize(errors, templates = nil)
+      message = errors.join("\n")
+
+      if templates
+        message << "\n"
+        message << "Templates:\n"
+        message << templates.map(&:inspect).join("\n")
+      end
+
+      super(message)
     end
   end
 

test/sandbox/test/rendering_test.rb

@@ -512,6 +512,11 @@ def test_raise_error_when_variant_template_file_and_inline_variant_call_exist
         end
       end
 
+    assert_includes(
+      error.message,
+      "ViewComponent::Template:"
+    )
+
     assert_includes(
       error.message,
       "Template file and inline render method found for variant 'phone' in " \