Guard against non-positive build code in ContinuousBuildCodeFormatter

Play Store versionCodes must be positive integers, so reject a
non-positive derived code.

Author: oguzkocer

lib/fastlane/plugin/wpmreleasetoolkit/versioning/formatters/continuous_build_code_formatter.rb

@@ -65,6 +65,11 @@ def build_code(major:, minor:, build_number:)
           prefix = (major * 10) + minor
           code = (prefix * (10**@build_digits)) + build_number
 
+          # Sanity check: Play Store versionCodes must be positive integers.
+          if code <= 0
+            UI.user_error!("Derived build code (#{code}) must be a positive integer")
+          end
+
           if code > MAX_PLAY_STORE_VERSION_CODE
             UI.user_error!("Derived build code (#{code}) exceeds the maximum allowed Play Store versionCode (#{MAX_PLAY_STORE_VERSION_CODE})")
           end

spec/continuous_build_code_formatter_spec.rb

@@ -79,6 +79,11 @@
       expect(described_class.new.build_code(major: 210, minor: 0, build_number: 0)).to eq(2_100_000_000)
     end
 
+    it 'raises when the derived code is not positive (all-zeros input)' do
+      expect { described_class.new.build_code(major: 0, minor: 0, build_number: 0) }
+        .to raise_error(/Derived build code \(0\) must be a positive integer/)
+    end
+
     it 'rejects a non-integer build_digits' do
       expect { described_class.new(build_digits: '6') }
         .to raise_error(/`build_digits` must be an integer, got: String/)