Fix bracket highlighter

highlighters/brackets/brackets-highlighter.zsh

@@ -52,18 +52,18 @@ _zsh_highlight_brackets_highlighter()
 
   # Find all brackets and remember which one is matching
   for (( pos = 0; $pos < ${#BUFFER}; pos++ )) ; do
-    local char=$BUFFER[pos+1]
+    local char="$BUFFER[pos+1]"
     case $char in
       ["([{"])
         levelpos[$pos]=$((++level))
         lastoflevel[$level]=$pos
-        _zsh_highlight_brackets_highlighter_brackettype $char
+        _zsh_highlight_brackets_highlighter_brackettype "$char"
         ;;
       [")]}"])
         matching[$lastoflevel[$level]]=$pos
         matching[$pos]=$lastoflevel[$level]
         levelpos[$pos]=$((level--))
-        _zsh_highlight_brackets_highlighter_brackettype $char
+        _zsh_highlight_brackets_highlighter_brackettype "$char"
         ;;
       ['"'\'])
         # Skip everything inside quotes

zsh-syntax-highlighting.zsh

@@ -107,7 +107,7 @@ typeset -gA ZSH_HIGHLIGHT_STYLES
 # Returns 0 if the buffer has changed since _zsh_highlight was last called.
 _zsh_highlight_buffer_modified()
 {
-  [[ ${_ZSH_HIGHLIGHT_PRIOR_BUFFER:-} != $BUFFER ]]
+  [[ "${_ZSH_HIGHLIGHT_PRIOR_BUFFER:-}" != "$BUFFER" ]]
 }
 
 # Whether the cursor has moved or not.