Main: Improve error reporting when failing to read from files

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "anyhow"
+version = "1.0.88"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e1496f8fb1fbf272686b8d37f523dab3e4a7443300055e74cdaa449f3114356"
+
 [[package]]
 name = "block-buffer"
 version = "0.10.4"
@@ -179,6 +185,7 @@ checksum = "e86697c916019a8588c99b5fac3cead74ec0b4b819707a682fd4d23fa0ce1ba1"
 name = "secrets-file-builder"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "handlebars",
  "serde_json",
  "url-escape",

Cargo.toml

@@ -9,6 +9,7 @@ repository = "https://git.nwex.de/networkException/secrets-file-builder"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+anyhow = "1.0.88"
 handlebars = "5.1.0"
 serde_json = "1.0.114"
 url-escape = "0.1.1"

src/main.rs

@@ -1,16 +1,20 @@
-use handlebars::{Context, Handlebars, Helper, HelperResult, JsonRender, Output, RenderContext, RenderErrorReason};
-use serde_json::{Map, Value};
-use std::{env, error::Error};
+use std::env;
 use std::fs;
+
+use anyhow::Result;
+
+use serde_json::{Map, Value};
 use url_escape;
 
-fn main() -> Result<(), Box<dyn Error>> {
+use handlebars::{Context, Handlebars, Helper, HelperResult, JsonRender, Output, RenderContext, RenderErrorReason};
+
+fn main() -> Result<()> {
     let mut handlebars = Handlebars::new();
 
     let path_to_contents = env::args().nth(1).expect("The first argument to be present.");
     let output_path = env::args().nth(2).expect("The second argument to be present.");
 
-    let contents = fs::read_to_string(path_to_contents).expect("To be able to open a file at the path passed as the first argument.");
+    let contents = fs::read_to_string(path_to_contents).expect("To be able to read the contents file at the path '{path_to_contents}' passed as the first argument.");
 
     let secret_inputs = env::vars().filter(|(key, _)| key.starts_with("SECRET_"));
 
@@ -21,7 +25,8 @@ fn main() -> Result<(), Box<dyn Error>> {
             panic!("Secret environment variable is not in format 'name:path_to_secret'");
         };
 
-        let secret_value = fs::read_to_string(path_to_secret)?;
+        let secret_value = fs::read_to_string(path_to_secret)
+            .expect("To be able to read in secret '{secret_key}' from path '{path_to_secret}'");
 
         println!("Registering secret '{secret_key}' from '{path_to_secret}'.");