3.8 catch tcl exception while executing exec ... guix

envfiles/python/3.8

 #%Module######################################################################
 #
 # python3.8 modulefile 20210616
+# last update! 20210618
 #
 
 proc ModulesHelp { } { 
@@ -22,8 +23,10 @@ setenv GUIX_PROFILE $GUIX_PROFILE
 
 conflict python/3.6 python/2.7
 
-exec sh -c "/usr/local/bin/guix install python@3.8 2>/dev/null"
-#exec sh -c . ${GUIX_PROFILE}"/etc/profile
+if {[catch {exec sh -c "/usr/local/bin/guix install python@3.8 2>/dev/null"} result]} {
+    puts "problem in executing guix"
+    puts "Reason : $result"
+}
 
 if { [module-info mode load] || [module-info mode switch2] } { 
     puts stdout "Please source your guix profile with:\nsource ${GUIX_PROFILE}/etc/profile;"