When I run the game, it works for a bit but then when the first asteroid

gets to the bottom I get this:

Traceback (most recent call last):
  File "/root/making_with_code/mwc1/unit3/lab_retro/nav_game.py", line 14, in <module>
    game.play()
  File "/root/making_with_code/mwc1/unit3/lab_retro/retro/game.py", line 80, in play
    agent.play_turn(self)
  File "/root/making_with_code/mwc1/unit3/lab_retro/asteroid.py", line 16, in play_turn
    game.remove_agent_by_name(self.name)
AttributeError: 'Asteroid' object has no attribute 'name'

retro/graph.py

@@ -0,0 +1,162 @@
+from retro.errors import GraphError
+
+class Graph:
+    def __init__(self, vertices=None, edges=None):
+        self.vertices = vertices or []
+        self.edges = edges or []
+
+    def __str__(self):
+        return '\n'.join(str(e) for e in self.edges)
+
+    def get_or_create_vertex(self, x, y):
+        for v in self.vertices:
+            if x == v.x and y == v.y:
+                return v
+        for e in self.edges:
+            if e.crosses(x, y):
+                return self.split_edge(e, x, y)
+        v = Vertex(x, y)
+        self.vertices.append(v)
+        return v
+
+    def get_or_create_edge(self, x0, y0, x1, y1):
+        v0 = self.get_or_create_vertex(x0, y0)
+        v1 = self.get_or_create_vertex(x1, y1)
+        new_edge = Edge(v0, v1)
+        for e in self.edges:
+            if e == new_edge:
+                new_edge.remove()
+                return e
+        return new_edge
+
+    def split_edge(self, edge, x, y):
+        """
+        Splits an edge by inserting a new vertex along the edge. 
+        """
+        if not edge.crosses(x, y):
+            raise GraphError(f"Can't split edge {edge} at ({x}, {y})")
+        self.remove_edge(edge)
+        v = Vertex(x, y)
+        self.vertices.append(v)
+        self.edges.append(Edge(edge.begin, v))
+        self.edges.append(Edge(v, edge.end))
+
+    def remove_edge(self, edge):
+        if edge not in self.edges:
+            raise GraphError(f"Edge {edge} is not in the graph")
+        self.edges.remove(edge)
+        edge.begin.edges.remove(edge)
+        edge.end.edges.remove(edge)
+
+    def render(self, terminal):
+        for v in self.vertices:
+            v.render(terminal)
+        for e in self.edges:
+            e.render(terminal)
+
+class Vertex:
+    CHARACTERS = {
+        "0000": " ",
+        "0001": "═",
+        "0010": "║",
+        "0011": "╗",
+        "0100": "═",
+        "0101": "═",
+        "0110": "╔",
+        "0111": "╦",
+        "1000": "║",
+        "1001": "╝",
+        "1010": "║",
+        "1011": "╣",
+        "1100": "╚",
+        "1101": "╩",
+        "1110": "╠",
+        "1111": "╬",
+    }
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+        self.edges = []
+
+    def __str__(self):
+        return f"({self.x}, {self.y})"
+
+    def __eq__(self, other):
+        return self.x == other.x and self.y == other.y
+
+    def neighbors(self):
+        vertices = []
+        for edge in self.edges:
+            if self == edge.begin:
+                vertices.append(edge.end)
+            else:
+                vertices.append(edge.begin)
+        return vertices
+
+    def render(self, terminal):
+        print(terminal.move_xy(self.x, self.y) + self.get_character())
+
+    def get_character(self):
+        u = self.has_up_edge()
+        r = self.has_right_edge()
+        d = self.has_down_edge()
+        l = self.has_left_edge()
+        code = ''.join([str(int(direction)) for direction in [u, r, d, l]])
+        return self.CHARACTERS[code]
+
+    def has_up_edge(self):
+        return any([v.x == self.x and v.y < self.y for v in self.neighbors()])
+
+    def has_right_edge(self):
+        return any([v.y == self.y and self.x < v.x for v in self.neighbors()])
+
+    def has_down_edge(self):
+        return any([v.x == self.x and self.y < v.y for v in self.neighbors()])
+
+    def has_left_edge(self):
+        return any([v.y == self.y and v.x < self.x for v in self.neighbors()])
+
+class Edge:
+    def __init__(self, begin, end):
+        if not isinstance(begin, Vertex) or not isinstance(end, Vertex):
+            raise ValueError("Tried to initialize an Edge with a non-vertex")
+        if begin.x < end.x or begin.y < end.y:
+            self.begin = begin
+            self.end = end
+        else:
+            self.begin = end
+            self.end = begin
+        if not (self.is_horizontal() or self.is_vertical()):
+            raise ValueError("Edges must be horizontal or vertical.")
+        if self.is_horizontal() and self.is_vertical():
+            raise ValueError("Self-edges are not allowed.")
+        self.begin.edges.append(self)
+        self.end.edges.append(self)
+
+    def __str__(self):
+        return f"{self.begin} -> {self.end}"
+
+    def render(self, terminal):
+        if self.is_horizontal():
+            with terminal.location(self.begin.x + 1, self.begin.y):
+                line = "═" * (self.end.x - self.begin.x - 1)
+                print(line)
+        else:
+            for y in range(self.begin.y + 1, self.end.y):
+                print(terminal.move_xy(self.begin.x, y) + "║")
+
+    def is_horizontal(self):
+        return self.begin.y == self.end.y
+
+    def is_vertical(self):
+        return self.begin.x == self.end.x
+
+    def crosses(self, x, y):
+        if self.is_horizontal():
+            return self.begin.y == y and self.begin.x < x and x < self.end.x
+        else:
+            return self.begin.x == x and self.begin.y < y and y < self.end.y
+
+    def remove(self):
+        self.begin.edges.remove(self)
+        self.end.edges.remove(self)