fix: prevent default browser behavior for tab and shift+tab when ther…

…e is no indent or unindent happening (athensresearch#209)

Co-authored-by: Adrien Lacquemant <github@alaq.io>
Co-authored-by: nthd3gr33 <codinginenglish@gmail.com>

src/cljs/athens/views/blocks.cljs

@@ -258,8 +258,10 @@
       (and (= key KeyCodes.DOWN) bottom-row?) (dispatch [:down uid])
       (and (= key KeyCodes.RIGHT) block-end?) (dispatch [:right uid])
 
-      (and (= key KeyCodes.TAB) shift) (dispatch [:unindent uid])
-      (= key KeyCodes.TAB) (dispatch [:indent uid])
+      (and (= key KeyCodes.TAB) shift) (do (.preventDefault e)
+                                           (dispatch [:unindent uid]))
+      (= key KeyCodes.TAB) (do (.preventDefault e)
+                               (dispatch [:indent uid]))
       (= key KeyCodes.ENTER) (do (.preventDefault e)
                                  (dispatch [:enter uid value index state]))
       (and (= key KeyCodes.BACKSPACE) block-start?) (dispatch [:backspace uid value]))))