fix(add): Catch empty dep name early

Author: epage

src/cargo/ops/cargo_add/crate_spec.rs

@@ -1,5 +1,6 @@
 //! Crate name parsing.
 
+use anyhow::bail;
 use anyhow::Context as _;
 
 use super::Dependency;
@@ -28,6 +29,9 @@ impl CrateSpec {
             .map(|(n, v)| (n, Some(v)))
             .unwrap_or((pkg_id, None));
 
+        if name.is_empty() {
+            bail!("dependency name cannot be empty");
+        }
         validate_package_name(name, "dependency name", "")?;
 
         if let Some(version) = version {

tests/testsuite/cargo_add/empty_dep_name/stderr.log

@@ -1,3 +1 @@
-thread 'main' panicked at src/cargo/core/dependency.rs:164:9:
-assertion failed: !name.is_empty()
-note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+error: dependency name cannot be empty