Don't ISE during recompilation of queries that produce warnings

The queries get recompiled without their full source buffer, which
some of the span machinery gets mad at.

Hack around it. (There are certainly better approaches.)

edb/common/span.py

@@ -89,8 +89,13 @@ def __getstate__(self):
         return dic
 
     def _calc_points(self):
+        # HACK: If we don't have an actual buffer (probably because we
+        # are recompiling after a schema change), just fake something
+        # long enough. Line numbers will be wrong but positions will
+        # still be right...
+        buffer = self.buffer.encode('utf-8') if self.buffer else b' ' * self.end
         self._points = ql_parser.SourcePoint.from_offsets(
-            self.buffer.encode('utf-8'),
+            buffer,
             [self.start, self.end]
         )
 

edb/server/compiler/rpc.pyx

@@ -128,7 +128,7 @@ cdef class SQLParamsSource:
         return self._cached_key
 
     def text(self):
-        return '<unknown>'
+        return ''
 
     def serialize(self):
         if self._serialized is not None:

edb/server/dbview/dbview.pyx

@@ -513,7 +513,7 @@ cdef class Database:
             try:
                 query_req = rpc.CompilationRequest.deserialize(
                     in_data,
-                    "<unknown>",
+                    "",
                     self.server.compilation_config_serializer,
                 )