container: lib_fetch: fix price parsing

- Fix check if price API is not set
- Fix check for invalid asset sequence
- Improve log messages

container/src/finance/lib/internal/lib_fetch.bash

@@ -669,8 +669,8 @@ function lib_fetch::__fetch_price()
 
   for _api in "${global_arg_api[@]}"; do
 
-    if ! lib_fetch::__parse_yaml "get-value" "price.${_api}" &>/dev/null; then
-      lib_utils::print_warning "'${_api}' price API is not set"
+    if [[ $(lib_fetch::__parse_yaml "get-value" "price.${_api}" 2>/dev/null) == "null" ]]; then
+      lib_utils::print_warning "price.${_api} is not set"
       continue
     fi
 
@@ -682,15 +682,17 @@ function lib_fetch::__fetch_price()
 
       case "$_member" in
         key)
-          [[ "$_value" == "null" ]] && lib_utils::print_warning "${_api} has empty ${_member}"
+          if [[ "$_value" == "null" ]]; then
+            lib_utils::print_warning "price.${_api}.${_member} is not set"
+          fi
           ;;
         asset)
-          if ! lib_fetch::__parse_yaml "get-value" "price.${_api}.${_member}" | grep -q "^- "; then
-            lib_utils::die_fatal "Invalid asset sequence!"
+          if [[ "$_value" =~ (^null$|^[^- ]) ]]; then
+            lib_utils::die_fatal "${_api} has invalid asset sequence"
           fi
           ;;
         *)
-          lib_utils::die_fatal "${_api} has invalid member: ${_member}"
+          lib_utils::die_fatal "price.${_api}.${_member} is invalid"
           ;;
       esac