feat: hopefully allow configuring zero as value

conf.v

@@ -40,9 +40,9 @@ fn get_env_var(prefix string, field_name string, file_suffix string) !string {
 
 [params]
 pub struct LoadConfig {
-    prefix string
-    file_suffix string = '_FILE'
-    default_path string
+	prefix       string
+	file_suffix  string = '_FILE'
+	default_path string
 }
 
 // load<T> attempts to create an object of type T from the given path to a toml
@@ -52,8 +52,12 @@ pub struct LoadConfig {
 pub fn load<T>(conf LoadConfig) !T {
 	mut res := T{}
 
-    // Later, this could be read from an env var as well.
-    path := conf.default_path
+	// This array allows us to determine later whether the variable is actually
+	// zero or just a null'ed struct field
+	mut has_value := map[string]bool{}
+
+	// Later, this could be read from an env var as well.
+	path := conf.default_path
 
 	if os.exists(path) {
 		// We don't use reflect here because reflect also sets any fields not
@@ -68,7 +72,11 @@ pub fn load<T>(conf LoadConfig) !T {
 					res.$(field.name) = s.string()
 				} $else $if field.typ is int {
 					res.$(field.name) = s.int()
+				} $else {
+					$compile_error('Unsupported config struct field type detected.')
 				}
+
+				has_value[field.name] = true
 			}
 		}
 	}
@@ -83,20 +91,14 @@ pub fn load<T>(conf LoadConfig) !T {
 				res.$(field.name) = env_value
 			} $else $if field.typ is int {
 				res.$(field.name) = env_value.int()
+			} $else {
+				$compile_error('Unsupported config struct field type detected.')
 			}
+
+			has_value[field.name] = true
 		}
 
-		// Now, we check whether a value is present. If there isn't, that means
-		// it isn't in the config file, nor is there a default or an env var.
-		mut has_value := false
-
-		$if field.typ is string {
-			has_value = res.$(field.name) != ''
-		} $else $if field.typ is int {
-			has_value = res.$(field.name) != 0
-		}
-
-		if !has_value {
+		if !(has_values[field.name] or { false }) {
 			return error("Missing config variable '$field.name' with no provided default. Either add it to the config file or provide it using an environment variable.")
 		}
 	}