ERROR: structure of query does not match function result type, Returned type text does not match expected type geometry

Question

Trying to write a function that returns the geometries of points interpolated in a line from a DEM and elevations but getting this error ERROR: structure of query does not match function result type. The query in the end of points should return the geometries of the startpoint, endpoint and interpolated points of an interval. This is my function:

test_get_slope_profile

CREATE OR REPLACE FUNCTION test_get_slope_profile(ways_id bigint, interval_ float default 10, way_table TEXT DEFAULT 'ways')
    RETURNS TABLE(p_geom geometry, elevation float)
    LANGUAGE plpgsql
AS $function$
DECLARE 
    way_geom geometry;
    length_meters float;
    length_degree NUMERIC;
    translation_m_degree NUMERIC;
BEGIN
    
    IF way_table = 'ways' THEN 
        SELECT geom, length_m, ST_Length(geom) 
        INTO way_geom, length_meters, length_degree
        FROM ways
        WHERE id = ways_id; 
    ELSEIF way_table = 'ways_userinput' THEN 
        SELECT geom, length_m, ST_Length(geom) 
        INTO way_geom, length_meters, length_degree
        FROM ways_userinput 
        WHERE id = ways_id; 
    END IF;


    translation_m_degree = length_degree/length_meters;
    DROP TABLE IF EXISTS dump_points;
    IF length_meters > (2*interval_) THEN 
        CREATE TEMP TABLE dump_points AS 
        SELECT (ST_DUMP(ST_Lineinterpolatepoints(way_geom,interval_/length_meters))).geom AS geom;
    
    ELSEIF length_meters > interval_ AND length_meters < (2*interval_) THEN 
        CREATE TEMP TABLE dump_points AS 
        SELECT ST_LineInterpolatePoint(way_geom,0.5) AS geom;
        interval_ = length_meters/2;
    ELSE
        CREATE TEMP TABLE dump_points AS
        SELECT NULL::geometry AS geom;
    END IF;
        

    RETURN query
    WITH points AS 
    (
        SELECT ROW_NUMBER() OVER() cnt, geom, length_meters 
        FROM (
            SELECT st_startpoint(way_geom) AS geom
            UNION ALL 
            SELECT geom FROM dump_points
            UNION ALL 
            SELECT st_endpoint(way_geom) 
        ) x
    )

    SELECT 'geom', SUM(idw.val/(idw.distance/translation_m_degree))/SUM(1/(idw.distance/translation_m_degree))::real AS elev
    FROM points p, get_idw_values(geom) idw
    WHERE p.geom IS NOT NULL 
    GROUP BY cnt 
    ORDER BY cnt;


END;
$function$;

ERROR:  structure of query does not match function result type
DETAIL:  Returned type text does not match expected type geometry in column 1.
CONTEXT:  PL/pgSQL function test_get_slope_profile(bigint,double precision,text) line 38 at RETURN QUERY
SQL state: 42804

Answer 1

In the RETURN query statement, don't do SELECT 'geom', SUM(...))::real AS elev but rather SELECT geom, SUM(...))::real AS elev

The former returns the text 'geom' while the later returns the column content, i.e. the geometry