Sweep handlers under separate function

For code readability and maintenance

src/imapdomo.skel

     local msg=$1
     local self
     self=$(basename "$0")
-    die "bug in $self (__MKIT_PROJ_VERSION__): $msg"
+    warn "bug in $self (__MKIT_PROJ_VERSION__): $msg"
 }
 
 mkcmd() {
       | sed 's/.lua$//'
 }
 
+handle() {
+    #
+    # Handle action $Action
+    #
+    local cmd       # imapfilter command
+    lshandlers | grep -qw "$Action" || {
+        warn "no handler for action: $Action.lua in $CfgDir/handlers"
+        return 2
+    }
+    cmd=$(mkcmd)
+    debug -v cmd
+    bash -n <<<"$cmd" || {
+        bug "bad syntax of cmd: '$cmd'"
+        return 3
+    }
+    if test -n "$CdTo";
+    then
+        cd "$CdTo" || {
+            warn "cannot chdir to: $CdTo"
+            return 3
+        }
+    fi
+    mkdir -p "$HeaderDir" || {
+        warn "cannot create header directory: $HeaderDir"
+        return 3
+    }
+    eval "$cmd"
+}
+
 main() {
     local Action    # what to do
     local Debug     # true if debugging
-    local cmd       # imapfilter command
     local CfgDir    # config directory
     local LogDir    # directory to store logs
     local HeaderDir # directory to store headers by save_header()
     local CdTo      # change dir to this before running imapfilter
     local Certs     # certificate storage
+    local es=0      # exit status of this function
     CfgDir="$IMAPDOMO_CFGDIR"
     LogDir="$IMAPDOMO_USER_CACHE/logs"
     HeaderDir="$IMAPDOMO_USER_CACHE/headers"
     Action="$1"; shift
     test -n "$Action" || usage -w "no action specified"
     debug -v Action CfgDir LogDir HeaderDir Debug CdTo
-    lshandlers | grep -qw "$Action" \
-     || die "no handler for action: $Action.lua in $CfgDir/handlers"
-    cmd=$(mkcmd)
-    debug -v cmd
-    bash -n <<<"$cmd" || bug "bad syntax of cmd: '$cmd'"
-    if test -n "$CdTo";
-    then
-        cd "$CdTo" || die "cannot chdir to: $CdTo"
-    fi
-    mkdir -p "$HeaderDir" || die "cannot create header directory: $HeaderDir"
-    eval "$cmd"
+    handle "$Action"; es=$?
+    return $es
 }
 
 main "$@"