added better error messages inspired by rustc/cargo

but not as good

mers/Cargo.lock

@@ -110,6 +110,17 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "acbf1af155f9b9ef647e42cdc158db4b64a1b61f743629225fde6f3e0be2a7c7"
 
+[[package]]
+name = "colored"
+version = "2.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2674ec482fbc38012cf31e6c42ba0177b431a0cb6f15fe40efa5aab1bda516f6"
+dependencies = [
+ "is-terminal",
+ "lazy_static",
+ "windows-sys",
+]
+
 [[package]]
 name = "errno"
 version = "0.3.1"
@@ -154,12 +165,24 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
 [[package]]
 name = "libc"
 version = "0.2.147"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
 
+[[package]]
+name = "line-span"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29fc123b2f6600099ca18248f69e3ee02b09c4188c0d98e9a690d90dec3e408a"
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.4.3"
@@ -177,6 +200,10 @@ dependencies = [
 [[package]]
 name = "mers_lib"
 version = "0.3.0"
+dependencies = [
+ "colored",
+ "line-span",
+]
 
 [[package]]
 name = "once_cell"

mers/src/main.rs

@@ -88,7 +88,7 @@ fn main() {
             let return_type = match run.check(&mut info_check, None) {
                 Ok(v) => v,
                 Err(e) => {
-                    eprintln!("check failed: {e}");
+                    eprint!("{}", e.display(&source));
                     std::process::exit(36);
                 }
             };