Issue #3414884 by pixelwhip: Add error handling for bp mixins

libraries/partials/mixins/_breakpoints.scss

@@ -15,6 +15,7 @@
 //  01 - Imports
 //------------------------------------
 
+@use 'sass:map';
 @use '../settings/breakpoints' as settings-breakpoints;
 @use '../functions/breakpoints' as functions-breakpoints;
 
@@ -36,7 +37,7 @@
       @content;
     }
   } @else {
-    @content;
+    @error '[ #{$name} ] is not defined in $breakpoints. Found: [ #{map.keys($breakpoints)} ]. Make sure the breakpoint you are trying to use is defined.';
   }
 }
 
@@ -58,7 +59,7 @@
       @content;
     }
   } @else {
-    @content;
+    @error '[ #{$name} ] is not defined in $breakpoints. Found: [ #{map.keys($breakpoints)} ]. Make sure the breakpoint you are trying to use is defined.';
   }
 }