feat: hopefully allow configuring zero as value

conf.v

@@ -52,6 +52,10 @@ pub struct LoadConfig {
 pub fn load<T>(conf LoadConfig) !T {
 	mut res := T{}
 
+	// 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
 
@@ -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.')
 			}
 
-		// 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
+			has_value[field.name] = true
 		}
 
-		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.")
 		}
 	}