man, mutt: avoid errors in nounset mode on Ubuntu 14 and 16

completions/man

@@ -75,11 +75,13 @@ _man()
     COMPREPLY=($(eval command ls "$manpath" 2>/dev/null))
     $reset
 
-    # weed out directory path names and paths to man pages
-    COMPREPLY=(${COMPREPLY[@]##*/?(:)})
-    # strip suffix from man pages
-    COMPREPLY=(${COMPREPLY[@]%$comprsuffix})
-    COMPREPLY=($(compgen -W '${COMPREPLY[@]%.*}' -- "${cur//\\\\/}"))
+    if ((${#COMPREPLY[@]} != 0)); then
+        # weed out directory path names and paths to man pages
+        COMPREPLY=(${COMPREPLY[@]##*/?(:)})
+        # strip suffix from man pages
+        COMPREPLY=(${COMPREPLY[@]%$comprsuffix})
+        COMPREPLY=($(compgen -W '${COMPREPLY[@]%.*}' -- "${cur//\\\\/}"))
+    fi
 
     # shellcheck disable=SC2053
     if [[ $prev != $mansect ]]; then

completions/mutt

@@ -31,14 +31,14 @@ _muttrc()
         shift
     done
 
-    if [[ -z $muttrc ]]; then
+    if [[ ! -v muttrc ]]; then
         if [[ -f ~/.${muttcmd}rc ]]; then
             muttrc=\~/.${muttcmd}rc
         elif [[ -f ~/.${muttcmd}/${muttcmd}rc ]]; then
             muttrc=\~/.${muttcmd}/${muttcmd}rc
         fi
     fi
-    printf "%s" "$muttrc"
+    printf "%s" "${muttrc-}"
 }
 
 # Recursively build list of sourced config files
@@ -54,7 +54,7 @@ _muttconffiles()
     shift
     while [[ ${1-} ]]; do
         newconffiles=($(command sed -n 's|^source[[:space:]]\{1,\}\([^[:space:]]\{1,\}\).*$|\1|p' "$(eval printf %s $1)"))
-        for file in "${newconffiles[@]}"; do
+        for file in ${newconffiles+"${newconffiles[@]}"}; do
             __expand_tilde_by_ref file
             [[ ! -f $file || $sofar == *\ $file\ * ]] && continue
             sofar+=" $file"