punk::repo handle missing fossil executable a little better

src/modules/punk/repo-999999.0a1.0.tm

@@ -125,10 +125,17 @@ namespace eval punk::repo {
             puts stdout [dict get $repostate warnings]
         }
         set fossil_prog [auto_execok fossil]
-        {*}$fossil_prog {*}$args
+        if {$fossil_prog ne ""} {
+            {*}$fossil_prog {*}$args
+        } else {
+            puts stderr "fossil command not found. Please install fossil"
+        }
     }
     interp alias "" fossil "" punk::repo::fossil_proxy
-    interp alias "" FOSSIL "" {*}[auto_execok fossil]
+
+    if {[auto_execok fossil] ne ""} { 
+        interp alias "" FOSSIL "" {*}[auto_execok fossil]
+    }
 
     proc askuser {question} {
         puts stdout $question
@@ -370,7 +377,9 @@ namespace eval punk::repo {
             if {$rt eq "fossil"} {
                 dict set resultdict repotype fossil
                 set fossil_cmd [auto_execok fossil]
-
+                if {$fossil_cmd eq ""} {
+                    error "workingdir_state error: fossil executable doesn't seem to be available"
+                }
                 if {[catch {punk::mix::util::do_in_path $repodir [list exec {*}$fossil_cmd status --all --differ --merge $abspath]} fossilstate]} {
                     error "workingdir_state error: Unable to retrieve workingdir state using fossil. Errormsg: $fossilstate"
                 }
@@ -760,6 +769,10 @@ namespace eval punk::repo {
         set startdir $opt_parentfolder
 
         set fossil_prog [auto_execok fossil]
+        if {$fossil_prog eq ""} {
+            puts stderr "Fossil not found. Please install fossil"
+            return
+        }
 
         set fossilinfo [exec {*}$fossil_prog info] ;#will give us the necessary config-db info whether in a project folder or not
         set matching_lines [punk::repo::grep {config-db:*} $fossilinfo]