replace quick-error with thiserror

The reason is tailhook/quick-error#20
and DrawingAreaErrorKind<E> from plotters.

Why not error-chain: rust-lang-deprecated/error-chain#240

Cargo.toml

@@ -17,4 +17,4 @@ serde_qs = "0.5"
 chrono = "0.4"
 serde = { version = "1.0", features = ["derive"] }
 hsluv = "0.1"
-quick-error = "1.2"
+thiserror = "1.0"

src/main.rs

@@ -1,4 +1,3 @@
-#[macro_use] extern crate quick_error;
 mod prom;
 mod render;
 

src/prom.rs

@@ -30,17 +30,13 @@ struct PromMetric {
 	values: Vec<(f64, String)>,
 }
 
-quick_error! {
-	#[derive(Debug)]
-	pub enum Error {
-		Fetch(e: reqwest::Error) {
-			display("failed to fetch data: {}", e)
-			from()
-		}
-		Prom(e: String) {
-			display("failed to execute query: {}", e)
-		}
-	}
+
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+	#[error("failed to fetch data: {0}")]
+	Fetch(#[from] reqwest::Error),
+	#[error("failed to execute query: {0}")]
+	Prom(String),
 }
 
 pub struct Metric {