plpgsql trigger parse error

I am having trouble getting a pl/PgSQL function to parse correctly and
my usual divide and conquer strategy is not working very well. The
full function appears at the bottom. When I simplified it to only the
first if (...) clause, it works. When I added the first else if (...)
clause, as shown immediately below, it fails.

create function deepsky_nodups() returns opaque as '
begin
if (NEW.suffix is NULL and NEW.component is NULL) then
if (exists (select id from deepsky where catalog = NEW.catalog and entry = NEW.entry and suffix is null and component is null)) then
return NULL;
end if;
else if (NEW.component is NULL) then
if (exists (select id from deepsky where catalog = NEW.catalog and entry = NEW.entry and suffix = NEW.suffix and component is null)) then
return NULL;
end if
end if;
return NEW;
end;
' language 'plpgsql';

create trigger ds_nodups before insert on deepsky
for each row execute procedure deepsky_nodups();

When it fires via the following insert

insert into deepsky (catalog, entry) values ('NGC', '1');

I get this error

NOTICE: plpgsql: ERROR during compile of deepsky_nodups near line 6
ERROR: parse error at or near "else"

I've stared at this so long I've run out of ideas on what might be
wrong. I started by cutting it down to the first if (...) and exists
clause. That works fine, i.e.,

create function deepsky_nodups() returns opaque as '
begin
if (NEW.suffix is NULL and NEW.component is NULL) then
if (exists (select id from deepsky where catalog = NEW.catalog and entry = NEW.entry and suffix is null and component is null)) then
return NULL;
end if;
end if;
return NEW;
end;
' language 'plpgsql';

is fine. The full function gives me a different error,

NOTICE: plpgsql: ERROR during compile of deepsky_nodups near line 20
ERROR: parse error at or near ";"

Here is the full function:

create function deepsky_nodups() returns opaque as '
begin
if (NEW.suffix is NULL and NEW.component is NULL) then
if (exists (select id from deepsky where catalog = NEW.catalog and entry = NEW.entry and suffix is null and component is null)) then
return NULL;
end if;
else if (NEW.component is NULL) then
if (exists (select id from deepsky where catalog = NEW.catalog and entry = NEW.entry and suffix = NEW.suffix and component is null)) then
return NULL;
end if;
else if (NEW.suffix is NULL) then
if (exists (select id from deepsky where catalog = NEW.catalog and entry = NEW.entry and component = NEW.component and suffix is null)) then
return NULL;
end if;
else
if (exists (select id from deepsky where catalog = NEW.catalog and entry = NEW.entry and component = NEW.component and suffix = NEW.suffix)) then
return NULL;
end if;
end if;
return NEW;
end;
' language 'plpgsql';

What am I missing?

roland
--
PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD RL Enterprises
roland(at)rlenter(dot)com 76-15 113th Street, Apt 3B
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