chore(solc): improve file not found error (#1611)

ethers-solc/src/error.rs

@@ -32,6 +32,13 @@ pub enum SolcError {
     Resolve(SolcIoError),
     #[error("File could not be resolved due to broken symlink: {0}.")]
     ResolveBadSymlink(SolcIoError),
+    #[error(
+        r#"Failed to resolve file: {0}.
+    --> {1:?}
+        {2:?}
+    Check configured remappings."#
+    )]
+    FailedResolveImport(SolcIoError, PathBuf, PathBuf),
     #[cfg(feature = "svm-solc")]
     #[error(transparent)]
     SvmError(#[from] svm::SolcVmError),

ethers-solc/src/resolver/mod.rs

@@ -368,7 +368,20 @@ impl Graph {
                     &mut resolved_solc_include_paths,
                 ) {
                     Ok(import) => {
-                        add_node(&mut unresolved, &mut index, &mut resolved_imports, import)?;
+                        add_node(&mut unresolved, &mut index, &mut resolved_imports, import)
+                            .map_err(|err| {
+                                match err {
+                                    SolcError::Resolve(err) => {
+                                        // make the error more verbose
+                                        SolcError::FailedResolveImport(
+                                            err,
+                                            node.path.clone(),
+                                            import_path.clone(),
+                                        )
+                                    }
+                                    _ => err,
+                                }
+                            })?
                     }
                     Err(err) => {
                         unresolved_imports.insert((import_path.to_path_buf(), node.path.clone()));