Fix lazy sequences not propagating AttributeError #1019 (#1021)

Fixes #1019

Author: mitch-kyle

CHANGELOG.md

@@ -6,12 +6,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Changed
- * Exceptions occurring during inlining during macroexpansion are no longer obscured by the outer macroexpansion exception (#1013) 
+ * Exceptions occurring during inlining during macroexpansion are no longer obscured by the outer macroexpansion exception (#1013)
 
 ### Fixed
  * Fix the behaviour of `nil` with several collection functions (#1011)
  * Fix a bug where `keys` and `vals` did not yield keys and values from sequences of map entries (#1018)
  * Fix a bug where `set` and `vec` do not produce collections of map entries when called on map arguments (#1020)
+ * Fix lazy sequences not propagating `AttributeError` (#1019)
 
 ## [v0.2.0]
 ### Added

src/basilisp/lang/seq.py

@@ -194,17 +194,15 @@ def is_empty(self) -> bool:
 
     @property
     def first(self) -> Optional[T]:
-        try:
-            return self.seq().first  # type: ignore[union-attr]
-        except AttributeError:
+        if self.is_empty:
             return None
+        return self.seq().first  # type: ignore[union-attr]
 
     @property
     def rest(self) -> "ISeq[T]":
-        try:
-            return self.seq().rest  # type: ignore[union-attr]
-        except AttributeError:
+        if self.is_empty:
             return EMPTY
+        return self.seq().rest  # type: ignore[union-attr]
 
     def cons(self, *elems: T) -> ISeq[T]:  # type: ignore[override]
         l: ISeq = self

tests/basilisp/seq_test.py

@@ -1,3 +1,5 @@
+import pytest
+
 from basilisp.lang import keyword as kw
 from basilisp.lang import list as llist
 from basilisp.lang import runtime as runtime
@@ -72,6 +74,16 @@ def inner_inner_seq():
 
     assert [1, 2, 3] == [e for e in s]
 
+    def raise_error(er):
+        raise er
+
+    s = lseq.LazySeq(lambda: raise_error(BaseException))
+    with pytest.raises(BaseException):
+        s.first
+    s = lseq.LazySeq(lambda: raise_error(AttributeError))
+    with pytest.raises(AttributeError):
+        s.first
+
 
 def test_empty_sequence():
     empty = lseq.sequence([])