new: bail out when failing to read compose file and be more explicit

bin/compose

@@ -2229,7 +2229,7 @@ get_compose_yml_location() {
         echo "$COMPOSE_YML_FILE"
         return 0
     fi
-    parent=$(while ! [ -e "./compose.yml" ]; do
+    parent=$(while ! [ -f "./compose.yml" ]; do
                  [ "$PWD" == "/" ] && exit 0
                  cd ..
              done; echo "$PWD"
@@ -2269,7 +2269,10 @@ get_compose_yml_content() {
     fi
     if [ -e "$COMPOSE_YML_FILE" ]; then
         debug "Found $WHITE$exname$NORMAL YAML file in '$COMPOSE_YML_FILE'."
-        COMPOSE_YML_CONTENT=$(cat "$COMPOSE_YML_FILE")
+        COMPOSE_YML_CONTENT=$(cat "$COMPOSE_YML_FILE") || {
+            err "Could not read '$COMPOSE_YML_FILE'."
+            return 1
+        }
     else
         debug "No compose file found. Using an empty one."
         COMPOSE_YML_CONTENT=""