Ensure build succeeds without uuid_unstable build flag

Closes #1403

lib/src/err/mod.rs

@@ -97,6 +97,13 @@ pub enum Error {
 		message: String,
 	},
 
+	/// There was a problem running the specified function
+	#[error("There was a problem running the {name}() function. {message}")]
+	InvalidFunction {
+		name: String,
+		message: String,
+	},
+
 	/// The wrong quantity or magnitude of arguments was given for the specified function
 	#[error("Incorrect arguments for function {name}(). {message}")]
 	InvalidArguments {

lib/src/fnc/rand.rs

@@ -138,4 +138,11 @@ pub mod uuid {
 	pub fn v7(_: ()) -> Result<Value, Error> {
 		Ok(Uuid::new_v7().into())
 	}
+	#[cfg(not(uuid_unstable))]
+	pub fn v7(_: ()) -> Result<Value, Error> {
+		return Err(Error::InvalidFunction {
+			name: String::from("rand::uuid::v7"),
+			message: format!("This function is not enabled in this version of SurrealDB."),
+		});
+	}
 }