Consistency with location and location?

src/spectator/fail_result.cr

@@ -41,12 +41,19 @@ module Spectator
     # Attempts to retrieve the location where the example failed.
     # This only works if the location of the failed expectation was reported.
     # If available, returns a `Location`, otherwise `nil`.
-    def location : Location?
+    def location? : Location?
       return unless error = @error.as?(ExampleFailed)
 
       error.location?
     end
 
+    # Attempts to retrieve the location where the example failed.
+    # This only works if the location of the failed expectation was reported.
+    # If available, returns a `Location`, otherwise raises `NilAssertionError`.
+    def location : Location
+      location? || raise(NilAssertionError.new("Source location of result unavailable"))
+    end
+
     # One-word description of the result.
     def to_s(io)
       io << "fail"

src/spectator/formatting/components/result_block.cr

@@ -71,8 +71,8 @@ module Spectator::Formatting::Components
     # Produces the location line.
     # This is where the result was determined.
     private def location_line(io)
-      location = if (result = @example.result).responds_to?(:location)
+      location = if (result = @example.result).responds_to?(:location?)
-                   result.location
+                   result.location?
                  end
       location ||= @example.location?
       return unless location

src/spectator/pending_result.cr

@@ -11,7 +11,7 @@ module Spectator
     getter reason : String
 
     # Location the pending result was triggered from.
-    getter location : Location?
+    getter! location : Location
 
     # Creates the result.
     # *elapsed* is the length of time it took to run the example.