FIX: Don't error out on nested top topic period param (#29275)

We're expecting the period param to be something that neatly coerces into a symbol. If we receive something like a nested parameter, this will blow up.

This commit raises an InvalidParameters exception in the case of a non-stringy period parameter.

app/models/top_topic.rb

@@ -45,11 +45,12 @@ class TopTopic < ActiveRecord::Base
   end
 
   def self.validate_period(period)
-    if period.blank? || !periods.include?(period.to_sym)
-      raise Discourse::InvalidParameters.new(
-              "Invalid period. Valid periods are #{periods.join(", ")}",
-            )
-    end
+    @invalid_period_error ||=
+      Discourse::InvalidParameters.new("Invalid period. Valid periods are #{periods.join(", ")}")
+
+    raise @invalid_period_error if period.blank? || !periods.include?(period.to_sym)
+  rescue NoMethodError
+    raise @invalid_period_error
   end
 
   private

spec/models/top_topic_spec.rb

@@ -34,6 +34,36 @@ RSpec.describe TopTopic do
     end
   end
 
+  describe ".validate_period" do
+    context "when passing a valid period" do
+      it do
+        expect { described_class.validate_period(described_class.periods.first) }.not_to raise_error
+      end
+    end
+
+    context "when passing a blank value" do
+      it do
+        expect { described_class.validate_period(nil) }.to raise_error(Discourse::InvalidParameters)
+      end
+    end
+
+    context "when passing an invalid period" do
+      it do
+        expect { described_class.validate_period("bi-weekly") }.to raise_error(
+          Discourse::InvalidParameters,
+        )
+      end
+    end
+
+    context "when passing a non-string value" do
+      it do
+        expect { described_class.validate_period(ActionController::Parameters) }.to raise_error(
+          Discourse::InvalidParameters,
+        )
+      end
+    end
+  end
+
   describe "#compute_top_score_for" do
     fab!(:user)
     fab!(:coding_horror)